1. Field of the Invention
The invention relates to growth chambers for Czochralski process crystal growth stations. More particularly the invention relates to reusable growth chambers employing one or more re-sealable caps with O-ring seals.
2. Description of the Prior Art
Known growth chambers used in Czochralski process crystal growth stations generally employ a temperature resistant chamber body with open ends that are sealed by mating caps, so that the chamber interior is isolated from ambient atmosphere. The chamber body is typically constructed of quartz with metal end caps. The open ends of the chamber body and the mating caps are typically sealed with a self-curing caulk, such as RTV silicone caulk. When RTV or other caulk is employed to seal the growth chamber for all practical purposes the sealed joint is permanently sealed. It becomes challenging to separate the cap or caps from the chamber body ends without damaging the chamber. Typically the chamber body damage caused during RTV caulk sealed component separation renders the chamber unserviceable for future crystal growth fabrication.
Known chamber caps often include cooling channels for circulation of cooling fluid during a crystal growth cycle, in order to compensate for their relatively faster and greater thermal expansion rate than the chamber body material, in order to avoid cracking of the latter. Chamber cracks developed during a crystal growth cycle greatly risks damage of the crystal boule and also destroys the growth chamber, with the consequences of either result causing undesirable economic loss. Therefore the cap cooling flow rate needs to be monitored so that the cap does not expand too quickly relative to the chamber body. Conversely the cap cooling flow rate must not be so fast, so that chamber body expansion does not break the chamber body/cap seal junction.